APropertyPrecomputed.h

/*
 * AUI Framework - Declarative UI toolkit for modern C++20
 * Copyright (C) 2020-2025 Alex2772 and Contributors
 *
 * SPDX-License-Identifier: MPL-2.0
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 */
 
#pragma once
 
#include "AObjectBase.h"
#include "ASignal.h"
#include "AUI/Util/AEvaluationLoopException.h"
#include <AUI/Common/detail/property.h>
#include <AUI/Common/React.h>

template<typename T>
struct APropertyPrecomputed final : aui::react::DependencyObserver {
   using Underlying = T;
   using Factory = std::function<T()>;
 
   template<aui::factory<T> Factory>
   APropertyPrecomputed(Factory&& expression): mCurrentValue([this, expression = std::forward<Factory>(expression)] { // NOLINT(*-explicit-constructor)
     aui::react::DependencyObserverRegistrar r(*this);
     return expression();
   }) {
 
   }
 
   APropertyPrecomputed(const APropertyPrecomputed&) = delete;
   APropertyPrecomputed(APropertyPrecomputed&&) noexcept = delete;
 
   template <ASignalInvokable SignalInvokable>
   void operator^(SignalInvokable&& t) {
       t.invokeSignal(nullptr);
   }

   void invalidate() override {
       mCurrentValue.reset();
       if (this->changed) {
           if (this->changed.isAtSignalEmissionState()) {
               mCurrentValue.setEvaluationLoopTrap();
               return;
           }
           emit this->changed(value());
       }
   }
 
   AObjectBase* boundObject() {
       return this;
   }
 
   [[nodiscard]]
   const T& value() const {
       aui::react::DependencyObserverRegistrar::addDependency(changed);
       return mCurrentValue;
   }
 
   [[nodiscard]]
   operator const T&() const {
       return value();
   }
 
   [[nodiscard]]
   const T& operator*() const {
       return value();
   }

   template <aui::invocable<const Underlying&> Projection>
   [[nodiscard]]
   auto readProjected(Projection&& projection) noexcept {
       return aui::detail::property::makeReadonlyProjection(*this, std::forward<Projection>(projection));
   }
 
   [[nodiscard]]
   const T* operator->() const noexcept {
       return &value();
   }
 
signals:
   emits<T> changed;
 
private:
   aui::lazy<T> mCurrentValue;
};
 
template<aui::invocable<> Factory>
APropertyPrecomputed(Factory&& f) -> APropertyPrecomputed<std::decay_t<std::invoke_result_t<Factory>>>;
 
static_assert(APropertyReadable<APropertyPrecomputed<int>>, "APropertyPrecomputed must be a APropertyReadable");

© 2025 AUI Framework Contributors. Documentation contributions included herein are the copyrights of their respective owners. The documentation provided herein is licensed under the terms of the GNU Free Documentation License version 1.3 as published by the Free Software Foundation. All trademarks are property of their respective owners.